Electromagnetic relay



Dec. 31, 1 95 7 c. v. BULLEN EIAL 2,818,478-

ELECTROMAGNETIC RELKY Fil ed Sept. 10, 1956 2 sneaks-sheet 1 FIG] /:i an? INVENTORS 100 IR. muow F165. [LARK M El/ZLEW Bra-Ag fi' MLN aha/4 United States Patent" ELECTROMAGNETIC RELAY Clark V. Bullen, Rockford, Ill., and John T. R. Wilson,

Sacramento, Calif., assignors to Barber-Colman Company, Rockford, 11]., a corporation of Illinois Application September 10, 1956, Serial No. 609,006

Claims. (Cl. 200-93) This invention relates to an electromagnetic relay of the polarized type having an armature movable into different active positions in response either to direct currents of opposite polarities or alternating currents of opposite phases.

The general object of the invention is to provide a polarized relay which, as compared to prior relays of the above character, is more sensitive to small signal currents, is more positive and reliable in its operation, and is of simpler construction.

Another object is to insure reliable operation of a polarized relay of the above character by moving the armature to a positively defined neutral position when the different signal currents are of negligibly small value.

A more detailed object is to provide a novel arrangement of flux producing coils and magnetic circuits for attraction of a freely floating armature selectively to any of three positively defined and angularly spaced positions under difierent current conditions in the coils.

The invention also resides in the novel and simple construction of the relay core providing the magnetic circuits.

Other objects and advantages of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings, in which:

Figure 1 is a perspective view of a relay embodying the novel features of the present invention with the protective cover removed.

Fig. 2 is a plan view with the cover removed, some parts being broken away and shown in section.

Fig. 3 is a sectional view taken along the line 3-3 of Fig. 2.

Fig. 4 is a fragmentary exploded perspective view of one pole piece and its encircling coil.

Fig. 5 is a sectional view taken along the line 5-5 of Fig. 2 with the cover in place.

Figs. 6, 7 and 8 are enlarged schematic plan views showing the positions of the armature under different current conditions.

The invention is shown in the drawings for purposes of illustration embodied in an electromagnetic relay having an armature 10 which is attracted into each of three different positions with respect to a core 11 selectively in response to different current conditions in a signal coil means 12 associated with the core. When the signal current is of zero or a negligibly small value, the armature is attracted to a neutral or null position (Figs. 2 and 6) by magnetic flux of an energizing or polarizing flux means 13. Signal currents of larger value and different characteristics or senses, for example, direct currents of opposite polarity or alternating currents of opposite phase, each produce a flux cooperating with the energizing flux to provide a resultant flux attracting the armature to the corresponding one of its other two positions shown in Figs. 7 and 8. In its different positions, the armature cooperates with contacts 14, 15 and 16 to control difierent electrical circuits (not shown) extending through the contacts.

To achieve sensitivity to small signal currents and insure ice reliable operation of the relay, the present invention contemplates free movement of the armature 10 into each of its three positions which are defined positively by seats angularly spaced from each other about a cavity or recess 17 receiving the armature. For this purpose, the core comprises three pole pieces 18, 19 and 20 converging toward but terminating short of each other in end faces spaced apart to form the cavity. The three armature seats are defined by abutments 21, 22 and 23 (Figs. 6, 7 and 8) rigid with the pole pieces and facing inwardly toward the cavity and each seat is disposed between two different pole pieces for attraction of the armature into the seat by magnetic flux threading the gap between the pieces. The abutments may be termed on or separately from the pole pieces, the two abutments 22 and 23 defining the seat for the neutral position of the armature in this instance being the end faces of two of the pole pieces 19 and 20. The third abutment 21 is the exposed face of a sheet 24 of the electric current conductive metal of U-shaped cross section telescoping with and secured to the end portion of the third or common pole piece 18.

Flux paths across the gaps between the adjacent ends of the pole pieces are completed by magnetic connections 25 joining the pieces at points spaced from their end faces. To simplify the construction of the core, the pole pieces are straight magnetic bars which are formed separately from the connections but are secured in abutting relation therewith to Iorm closed magnetic joints. While two connections may be used, there are three in this instance of arcuate shape arranged in a circle on one end of a cylindrical base 26 of nonmagnetic material and having their adjacent ends spaced apart to receive and abut the outer end portions of the pole pieces which are disposed radially of the base.

The pole pieces 18, 19 and 20 and the connections 25 are laminated and are of rectangular cross section with the same thickness axially of the base 26, the connections being secured to the latter by screws 27 extending through holes in the laminations and the base and threaded into a bottom housing plate 28 of insulating material. To secure the pole pieces in place, flat plates 29 overlapping the abutting end portions or the connections and the pieces are clamped against the same by screws 30 threaded into the housing plate and extending through holes in the base and longitudinal slots 31 (Fig. 2) which are formed in the pieces for adjustment of the latter radially relative to the base. At their inner ends, the pole pieces are hat, the two pieces 19 and 20 defining the neutral seat being tapered outwardly for increased rlux densities at the ends.

While the means 13 providing the energizing flux in the tapered pole pieces 19 and 20 ror attracting the armature 10 into its neutral seat may constitute permanent magnets in the case of unidirectional signal current, it is preferred to use one or more multiple turn windings or coils which may be utilized for alternating as well as direct current signals and whose energization may be varied to change the amount or energizing flux after assembly of the relay parts. in this instance, there are two energizing coils 13 one for each of the tapered pole pieces and each wound around a bobbin 32 of insulating material which telescopes closely over and is supported on the associated pole piece While leaving the inner end portion of the latter exposed. The signal coil means 12 also cornprises one or more coils, herein one, Wound on an insulating bobbin 33 telescoping over the third pole piece 18 and the laterally spaced parallel legs of the U-shaped sheet 24. Due to formation or the pole pieces 18, 19 and 20 as elongated members separate from the connections 25, the

T a complete the electrical circuits through the contacts 14 ,152 and 16;:thea armature .itself is adapted to conduct currentand, thereby constitute a. movable. contact of. thev relay. While the armature may be a ball, it is preferred to use a cylinder as shown for engagement with the fixed contactsialong lines-.rather than ati points. wHerein; thearmaturecomprises aistack. of axially alined annular'l'ami: nations=34g (Big 5). of magncticxmater-ial secured rigidly together. as cement) and: telescoping oven a pin" 35 which projects from. opposite; ends of the staclc. To improve. its conductivity the armature preferably is: platedrontits.

exterior with. a,highly conductivematerial: suchas. silver. The, conductive sheet: 24'.on the; common poleepiece 18 provides a common contact; 14aengageablewith the armature .in both of 'itSl active: positions; The-other contacts 15 and 16-. are formed as: reversely -bentends. of I fingers.

36tproje'ctin g inwardly fromt fiat-resilient: strip s: 37 of-conductingmaterial'. *I-I'erein; theisheetand: the stripsare formed!of' hammeredusilver.approximately: .002 of an inch thick. Thestrips are secured intslotsformed in lugs 38 on 1 the :inner' ends of z'the energizing. coil bobbins 32 witheachtof the contactslthereonlprojecting between the commonpolepiece and'athe associatedione of the=tapered pole pieces 19 and 20; the contacts. thus being resiliently supportedifor'sliding contact-with:the armature. Thin sheets 39 of insulation separate the'contacts from' theassociated polepiecesand the ends ofr the tapered pole pieces 19 and 20.-may, iftdesired alsobe,covered by thinsheets-40 of insulation-as shown-.in Figs 8.

Toconfine the armature axially within the-cavity 1.17, the bottom housing-plate 28 andan inverted cupshaped cover 41 of insulating material carry-lugsfl projecting toward thecavity and providingflat abutment faoesengageable with theprojecting ends of the: armature pin 35 but spaced apart to provide clearance for free sliding of the. armature without cocking, the endsof the pin being rounded to-facilitate such sliding; 'Electricalcin cuits totbe completedMhrough-the contacts are-connected to the respective contact strips 37 and the sheet 24 which projectupwardly throughthe top of the cover 41 (Big; 5).

The operation of the; relay may best be described in connection with Figs. 6, 7 and-tfiwhich show the-distribution of flux:undcr'diiferent conditions of current flow through the coils12= and 13; Assuming no-current is flowing in the signal coil 12 and that direct current is flowing in-equal amountsinthe energizingcoils to produce a flux whosedirection in -the-tapered pole piece- 19-. on the left is toward the cavity Hand in the-tapered pole piece 20'on-theright is away from the cavity,- the-fiux will be distributed generally-asshownby the lines 43in Fig. 6, the arrowheads indicatingdirection'. Substantially all of thisilux traverses the gap-betweenthe tapered-pole pieces to attract'thearmatureagainstthetwoabutments 22 and 23 thereof and into the neutral-seat defined thereby. As it leaves the right-polepiece, this flux divides between a path through the coreconnection ZSabutting bothpole pieces and-ano-therpathextending past the outer end of the common pole piece18 and through the other two connections as indicated bythe-lines 43, themajor portion of this flux followingtheshQrterpath. In its neutral position, the armature is'spaced from and out of engagement with all of the fixed-contacts 14; and 16. Flux in the common pole piece 18 is substantially zero because the flux'frorn one energizing coil-tending to thread this pole pieceopposcs that of'theother energizing coil.

With the same energizing flux ancl'with signal current fiowing-iri the coil' 12 in a direction to produce a flux therein whose direction is away from the cavity 17, such flux tends to follow two paths represented by arrowed lines 44 in Fig. 7.and extending through the respective taperedpolepieces19, and 20. The direction of this flux with respect ,to,the energizing fluxisthe same-in the left, pole piece;- 19, but; is opposite in theright; pole, piece; 20.. nder. th e conditions, the; resnltantflux inthe air gap. between the left pole piece and the common pole-.piece.

18 is greater than the flux in either of the other gaps, the

.fluxintherrightrpole piece, and. thereforein. the, other, gaps.

being substantially zero when the amount of signal current flux in each tapered pole piece is equal approximately to the energizing flux. Thus, the armature is attracted into its active seat defined by the common abutment 21 and the abutment face 22 of theleft pole piece and engages the left contact 15 and the common contact 14 to complete the external circuit between.the.,.contacts.

Upon, energizationlof the. signalcoil 12 with current flowingjtlierethrough in;the,oDPQsite direction, the signal flux follows, the same pathstasbeforetbut inloppositejdirections as indicated by arrowed lines 45 in Fig. 8. The resultant flux in the gapbetween the right tapered pole piece 20 and the, common pole piece 18 then is greater than in either of'the other gaps and the armature is attracted into the corresponding seat to engage the right contact 16 and complete the circuit between the latter andthe common contact 14. Upon deenergization of the signal coil; the armature=again is attractedzinto the neutral seat by the energizing flux. .In the case of. alternating currentsin the;energizing and signal= coils": 12 and 13, the operation is substantially the same when 'the signalflcurrent is. in phaseor outtof phase withithe energizing current, the arrowheads on:- the various flux path lines: representing the instantaneous directions: of the flux.

It will be apparent that the relay is reliable in itsopera tion becausethe armature: 10'; by virtue-of itspositive seating'againstthe abutments 21; 22 and 2Bineachof its three positions, tends to remain in such position when subjected tovibrations.

by -'theangular spacing of the polepieces "18-, 19 and '20 with the-signal andenergizing coils Hand 13 arranged to direct-:magnetic. fiux selectively across only one of the three gaps between-adjacent polepiecesata-time. Theformation of the-pole pieces as' straight bars separate from the connections 25 facilitates mounting of thecoils: thereon andenables the connectionsto be-identical thereby simplifying-manufacture and assembly of these parts.

We claim-as=our invention:

1. A relay having in combination, a hollow cylindrical base of nonmagnetic material, a-mag-netic -c0re comprising three -arcuate-segrnents of-the same construction extending around and secured against one end of said-base in angularlyspacedrelation-withtheir adjacent ends spaced apart and facing toward each other, three elongatedmagnetie pole pieceseach disposed" between and abutting said opposed ends of a different pair of said segments andprojecting radially andginwardly therefrom toward-but short of the other pole-pieces to define a cavity, a magnetic armature smaller than and freely movable within .said' cavity abutments rigid with said pole pieces andeugageable with said armature to confine the, movements thereof to three angularlly spaced'positions, a plurality of coils encircling said pole pieces andoperable under different conditions, of energizaticm to produce a resultantfiux attracting said armature selectively into eachof said three different'p.ositions,,,andcontact'means cooperating with said."

armature, to completeditferent electrical circuits when the armature is in saiddifferent'positions.

2'. A relay having, in combination, a core comprising first, secondandjthird elongatedpol'e pieces of magnetic materialconnected' together atvtheir outer ends'by magnetic members and converging toward each other with" their inner ends spacedapart and'defi'ning a cavity, a magnetic armature -sma'llerthan andfreely movable within said cavity and adapted to conductelectric current, a contact-strip, covering theinner, end ofsaidfi'rst piece, ,,s,airl.v strip andihe innercnrlsofsaid sccondahdthird pieces, abutting; ,said, armature and .defi'ninza hrcc .angularly spaced). seats therefor, I two'icontacts one ,silmlpnted behind,

of said seats between said-first pieceendithe .othcrpieees.

Such positive "seating is -made possible by a free floating mounting of the armature and for abutment with the armature when the latter is disposed in the corresponding seat, energizing coils encircling said second and third pole pieces and operable when activated to produce an energizing flux attracting the armature against the seat between the pieces, and a signal coil encircling said first piece to produce flux cooperating with said energizing flux to provide different resultant fluxes attracting said armature into the respective seats adjacent the first piece when the coil is energized in opposite senses.

3. A relay having, in combination, a core of magnetic material having angularly spaced first, second and third pole pieces connected together magnetically and converging toward but terminating short of each other to define a cavity with an air gap between each pair of adjacent pole pieces, a freely movable armature of magnetic material disposed within and smaller than said cavity and adapted to conduct electric current, a plurality of abutments rigid with said pole pieces and facing inwardly toward said cavity to engage said armature and define three angularly spaced seats therefor each disposed between two adjacent pole pieces, flux means operable to produce an energizing flux in the gap between said first and second pole pieces to attract said armature into the corresponding seat between the pieces, signal coil means encircling part of said core and operable to produce flux cooperating with said energizing flux to attract said armature into the seat between said third and first pole pieces when the coil means is energized in one sense and into the seat between said third and second pole pieces when the coil means is energized in the opposite sense, and contact means engageable with said armature to complete an electric circuit therethrough when the armature is in each of said seats adjacent said third pole piece.

4. A relay having, in combination, a core of magnetic material having three angularly spaced pole pieces converging toward and terminating short of each other in end faces defining a cavity, said pole pieces being connected magnetically at points spaced from said faces, an armature smaller than and freely movable within said cavity, abutments Ilgld with said pole pieces and defining three angularly spaced seats for said armature each disposed between two different pole pieces, energizing coils encircling parts of said core and operable when energized to produce an energizing flux in two of said pole pieces attracting said armature into the seat between the pieces, a signal coil encircling another part of said core and operable to provide a flux in the third pole piece cooperating with said energizing flux to produce resultant fluxes attracting the armature into the respective seats adjacent the third piece when the coil is energized in opposite senses, and contact means cooperating with said armature to complete a different electric circuit when the armature is in each of said seats adjacent said third pole piece.

5. A relay having, in combination, a magnetic core having first, second and third pole pieces terminating in pole faces angularly spaced around and defining a cavity with an air gap between each pair of adjacent pieces, magnetic connections between said pole pieces at points spaced from said faces, a freely movable armature of magnetic material disposed within and smaller than said cavity, abutments rigid with said pole pieces and facing toward said cavity to engage said armature and define three angularly spaced seats for the armature each disposed between two diiferent ones of said pole pieces, flux means providing an energizing flux in said first and second pole pieces to attract said armature into the gap and the corresponding seat between the pieces, signal flux means operable to provide a flux in said third pole piece cooperating with said energizing flux to produce a resultant flux attracting said armature against the seat between the third and first pole pieces when the means is energized in one sense and a resultant flux attracting the armature against the seat between the third and second pole pieces when the means is energized in the opposite sense, and contact means cooperating with said armature to complete an electric circuit when the armature is in each of said seats adjacent said third pole piece.

References Cited in the file of this patent UNITED STATES PATENTS 1,492,913 Wood May 6, 1924 2,253,856 Harrison Aug. 26, 1941 2,732,458 Buckingham Ian. 24, 1956 

